Thirty male Macaca fascicularis monkeys will be used in a combination basic and clinical research effort to investigate the pathophysiology of varicocele, the single most prominent clinical finding associated with infertility in human males. Five groups of five monkeys will be started in the first year; they will receive the following surgical procedures: (1) sham control, (2) varicocele induction by restriction of left renal vein, (3) and (4) same as (2); (5) varicocele induction and left adrenalectomy. These monkeys will be studied for 31 months using semen analysis (including biochemical assays), scrotal thermography and thermister readings, testicular biopsies (evaluated by light and both transmission and scanning electron microscopy), and radioimmunoassays for testosterone and gonadotropins. Groups (3) and (4) will have varicocelectomies performed at one and two years, respectively. A sixth group will be started in year 2 to study the pharmacologic effects of alpha and beta-adrenergic blocking agents on varicocele development. Clinical patients with varicocele and age-matched normal control men will be studied using semen analysis, peripheral hormone levels, and scrotal thermography. Patients will also be studied post-varicocelectomy. By using the same noninvasive and mildly invasive (veinpuncture) procedures in the monkey model and in humans we can extrapolate the invasive finding (testicular biopsies) from the animal model to man. This project will provide a unique opportunity to learn about the pathophysiology of varicocele, to study the progressive development, its effects on testicular and sperm morphology, changes in accessory sex gland function, scrotal thermal patterns, and hormone levels. Comparison of the induced varicocele in the animal model to that spontaneously occuring in man will provide significant data for the evaluation of the infertile male with varicocele and will contribute to the successful treatment of the condition.